Temperature-controlled cargo containers, such as, for example, refrigerated trucking trailers, are of course well known for transporting food or other products that need to be shipped under predetermined temperature-controlled conditions. Conventionally, a refrigerated trailer usually has a refrigeration unit mounted upon an upper region of the front wall member of the trailer wherein a major portion of the refrigeration unit usually projects outwardly through the front wall member of the trailer so as to effectively be located externally of the trailer, however, relatively warm air inlet and relatively cooled air outlet portions of the refrigeration unit are fluidically connected to the interior cargo space of the refrigeration trailer so as to continuously recirculate cooled or refrigerated air throughout the interior cargo space of the refrigeration trailer. More particularly, the relatively warm air is effectively sucked into the air inlet portion of the refrigeration unit from regions of the refrigeration trailer which are disposed within the vicinity of the floor of the trailer, while cooled or refrigerated air is effectively forced outwardly from the air outlet portion of the refrigeration unit and into those regions of the refrigerated trailer which are disposed within the vicinity of the ceiling of the refrigeration trailer. In addition, in order to facilitate or cause the cooled or refrigerated air to in fact traverse substantially the entire axial extent of the interior cargo space within the refrigerated trailer such that a substantially uniform temperature level is in fact achieved throughout the entire axial length or extent of the interior cargo space of the refrigerated trailer, axially extending ducting is provided within the vicinity of the interior ceiling surface portion of the refrigerated trailer, and suitable vents are provided at predeterminedly spaced axial locations within such ducting in order to permit the cooled refrigerated air to flow outwardly from the ducting at such predetermined axial locations along the axial extent of the refrigeration trailer.
In addition, a vertically oriented air return bulkhead is operatively connected to the front wall member of the refrigeration trailer so as to substantially extend vertically between the air inlet portion of the refrigeration unit and the floor region of the refrigeration trailer. The air return bulkhead effectively defines a hollow enclosure whereby, for example, peripheral portions of the air return bulkhead can be attached to the front wall member of the refrigerated trailer, however, the central portion of the air return bulkhead is effectively spaced from the front wall member of the refrigeration trailer so as to effectively define a relatively warm return air conduit from the floor region of the refrigeration trailer to the air inlet portion of the refrigeration unit. An example of such a conventional mounting of a refrigeration unit upon a front wall member of a refrigerated trailer, the use of such axially extending ducting within the internal ceiling region of the refrigerated trailer in order to conduct relatively cooled air toward the rear portion of the refrigerated trailer, and the use of the an air return bulkhead mounted upon the front wall member of the refrigerated trailer so as to effectively define a relatively warm air return conduit for conducting relatively warm air from the floor region of the refrigeration trailer to the air inlet portion of the refrigeration unit, is disclosed, for example, within FIG. 1 of U.S. Pat. No. 7,351,136 which issued to Nelson et al. on Apr. 1, 2008, such disclosure being incorporated herein by reference.
While the air return bulkhead as disclosed within the aforenoted patent to Nelson et al. is operatively satisfactory, it is noted that periodically the refrigeration unit may require repair or maintenance. For example, as a result of the continuous refrigeration cycling of the refrigeration unit, wherein relatively warmed air is being continuously returned from the interior cargo space of the refrigerated trailer back toward the air inlet portion of the refrigeration unit such that the refrigeration unit can cool the relatively warmed air and effectively discharge relatively cooled or refrigerated air back out into the interior cargo space of the refrigerated trailer within the vicinity of the ceiling member of the refrigerated trailer, the filter member, normally disposed or operatively associated with the air inlet portion of the refrigeration unit, may need to be periodically cleaned of debris, dust particles, or the like. Accordingly, the air return bulkhead must be entirely removed from its mounted position upon the front wall member of the refrigerated trailer in order to permit repair or maintenance to effectively gain access to the air inlet portion of the refrigeration unit or to other operational components of the refrigeration unit. It can therefore be readily appreciated that the removal or disassembly of the entire air return bulkhead from its mounted position upon the front wall member of the refrigerated trailer is therefore oftentimes quite time-consuming and tedious in view of the relatively large number of fasteners, mounting brackets, or the like, normally utilized or employed to fixedly secure the entire return air bulkhead to or upon the front wall member of the refrigeration trailer.
A need therefore exists in the art for a new and improved air return bulkhead wherein, for example, only a portion of the return air bulkhead needs to be readily, easily, and quickly removed so as not to comprise a tedious process normally or conventionally involving the removal of the entire air return bulkhead from its mounted position upon the front wall member of the refrigerated trailer, and wherein the removal of only a portion of the return air bulkhead will in fact be sufficient so as to permit repair or maintenance personnel to gain access to the lower region of the refrigeration unit without requiring an inordinate amount of time. In addition, a need exists in the art for a new and improved air return bulkhead wherein the removable portion of the air return bulkhead can not only be readily, easily, and quickly engaged with, and disengaged from, the residual main portion of the return air bulkhead which is fixed to or mounted upon the front wall member of the refrigeration trailer, but in addition, the removable portion of the air return bulkhead can likewise also be readily, easily, and quickly fixed to or mounted upon the front wall member of the refrigeration trailer.